The multiples of forty up to 1000 are
40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920 960 and 1000
As a general rule to find a multiple of forty take any multiple of 4 and add zero at the end.
When multiplying by 40 you can multiple the number first by 4 then add a zero to multiply by ten because 4*10 =40
Eg. 15*40
15*4 = 60
60 * 10 = 600
15*50 = 600
